postload css

loadcss

(function() {
    'use strict';

    function loadCssWithLink() {
        var l = document.createElement('link');
        l.rel = "stylesheet";
        l.href = 'css/css.css';
        var sc = document.getElementsByTagName('script')[0];
        sc.parentNode.insertBefore(l, sc);
    }

    function loadCssWithAjax() {
        var xhr = new XMLHttpRequest();
        xhr.open('GET', 'css/css.css', true);
        xhr.onreadystatechange = function() {
            if (xhr.readyState === 4) {
                if (xhr.status !== 200) {
                    loadCssWithLink();
                }
            }
        };
        xhr.timeout = 3000;
        xhr.send();
    }

    var cutsTheMustard = function() {
        if (
            'querySelector' in document &&
            'addEventListener' in window &&
            'XMLHttpRequest' in window
        ) {
            return true;
        } else {
            return false;
        }
    };

    if (cutsTheMustard() === true) {
        loadCssWithAjax();
    } else if (cutsTheMustard() === false) {
        loadCssWithLink();
    }
})();